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Brajesh K. Singh is an environmental scientist and microbiologist by training, and his current research interests include understanding the ecology of cultivable and uncultivable microorganisms and their roles in ecosystem functioning.

Richard D. Bardgett is Professor of Ecology at Lancaster University, UK. He is an ecologist with interests in understanding the ecology of linkages between plant and soil biological communities and their roles in ecosystem functioning under global change.

Pete Smith is Professor of Soils and Global Change at the University of Aberdeen, UK. He is an ecosystem modeller with an interest in soils, climate change and greenhouse gas emissions, and he wants to help find ways to mitigate climate change.

Subjects

Abstract

Microbial processes have a central role in the global fluxes of the key biogenic greenhouse gases (carbon dioxide, methane and nitrous oxide) and are likely to respond rapidly to climate change. Whether changes in microbial processes lead to a net positive or negative feedback for greenhouse gas emissions is unclear. To improve the prediction of climate models, it is important to understand the mechanisms by which microorganisms regulate terrestrial greenhouse gas flux. This involves consideration of the complex interactions that occur between microorganisms and other biotic and abiotic factors. The potential to mitigate climate change by reducing greenhouse gas emissions through managing terrestrial microbial processes is a tantalizing prospect for the future.

Key points

Microorganisms are the most diverse and dominant organisms on the planet and are vital for ecosystem functioning. However, most of them cannot yet be cultured in the laboratory.

Microbial processes have a central role in the global fluxes of the key greenhouse gases carbon dioxide, methane and nitrous oxide, and these processes are likely to respond rapidly to climate change.

An improved mechanistic understanding of microbial controls of terrestrial greenhouse gas fluxes is essential to improve the prediction of climate models.

New and emerging molecular tools are now available to quantify the diversity of uncultivable microorganisms and their metabolic processes, which will help to improve our manipulation of their feedback responses to climate change.

There is huge potential to manage and manipulate microbial processes to mitigate climate change by reducing greenhouse gas emissions from terrestrial ecosystems.

To achieve this, an interdisciplinary approach is required that includes microbial ecology, environmental genomics, soil and plant science, and ecosystem modelling.

Singh, B. K.et al.Effect of afforestation and reforestation of pastures on the activity and population dynamics of methanotrophic bacteria. Appl. Environ. Microbiol.73, 5153–5161 (2007). This work provides the first evidence that soil microorganisms reduce CH4 flux as a result of land use change.

Ginolhac, A.et al.Phylogenetic analysis of polyketide synthase I domains from soil metagenomic libraries allows selection of promising clones. Appl. Environ. Microbiol.70, 5522–5527 (2004). This study uses a mathematical formula to estimate microbial diversity and suggests that at least 2 million clones need to be sequenced to cover the diversity of a microbial community in a soil sample.

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Competing interests

Corresponding author

Glossary

Radiative forcing

A measure of the influence that a factor has in altering the balance of incoming and outgoing energy in the Earth–atmosphere system. It is an index of the importance of the factor as a potential climate change mechanism.

Heterotrophic

Of an organism: able to use organic compounds as nutrients to produce energy for growth.

Autotrophic

Of an organism: able to synthesize organic carbon from the fixation of inorganic carbon (for example, by photosynthesis or chemosynthesis).

Dissolved inorganic carbon pool

The sum of inorganic carbon in solution.

Net primary production

The part of the total energy fixed by autotrophic organisms that remains after the losses through autotrophic respiration.

Methanogenesis

The process by which methane is produced by microorganisms (mainly archaea).

Methanotrophic

Of an organism: able to use methane as a nutrient to produce energy for growth.

Nitrification

The conversion of NH3 into a more oxidized form such as nitrate or nitrite.

Denitrification

The reduction of oxidized forms of nitrogen to N2O and dinitrogen.

Reactive nitrogen

Nitrogen in a form that can undergo biological transformations, such as nitrite and nitrate.

Permafrost

Soil that remains permanently frozen.

Recalcitrant carbon

A form of carbon that is resistant to microbial decomposition owing to its chemical structure and composition.

Peatland

An area dominated by deep organic soils.

Water table

The level at which the groundwater pressure is the same as the atmospheric pressure.